Aprostocetus bromi (Kostjukov), 1978

Johnson, Paul J., Yefremova, Zoya A., López, Juan Manuel Perilla & Yegorenkova, Ekaterina N., 2018, Aprostocetus chilophagae new species (Hymenoptera: Eulophidae) from South Dakota, with taxonomic notes on A. bromi (Kostjukov) and A. nebraskensis (Girault), Zootaxa 4514 (4), pp. 473-486 : 475-480

Aprostocetus bromi (Kostjukov)

( Figs. 1–3 , 5–12a )

Tetrastichus bromi Kostjukov 1978: 458 ; Perilla López et al. 2015a: 115, 2015b: 297

Aprostocetus bromi , of Kostjukov and Kosheleva 2006: 104

Material examined. Holotype, ♀, [ UKRAINE] Kiev, Kozarovychi, reared from Bromis inermis , 16.vii.1949 (Kryshtal) ( ZISP). Four ♀, paratypes with the same labels, also at ZISP. No male was included in type series.

Additional material examined: RUSSIA, 3 ♀, 1 ♂, Ulyanovsk, 54°36' N, 48°51'E, 20.vi.2015, reared and captured by aspirator on inflorescences of Bromus inermis , Stenodiplosis sp. 26-27.vi.2015. coll. E. Yegorenkova ; 6 ♀, 3 ♂, Russia, Staraya Mayna , 54°36′N 48°55′E, 7.vii.2015, reared and captured by aspirator on inflorescences of Bromus inermis , Stenodiplosis sp. 13-18.vii.2015, coll. E. Yegorenkova ; 6 ♀, 2 ♂, Samara, 53°47'N 49°90'E, 1.vii.2015, reared and captured by aspirator on inflorescences of Bromus inermis , Stenodiplosis sp. 3.vii.2015, coll. E. Yegorenkova. U.S. A, 15 ♀, South Dakota: Brooking Co. 2 mi. E. of Bushnell , 44°19'46''N, 96°36'26''W swept from Bromus inermis , 9.vi.2014 coll P.J. Johnson ; 2 ♂, U.S.A.: South Dakota: Brooking Co. 2 mi. E. of Bushnell , 44°32'54''N, 96°60'83''W, reared from Bromus inermis along road, 22.vi.2014 coll P.J. Johnson (1 ♂ on slide), ex. Stenodiplosis bromicola Marikovskij & Agafonova ; 4 ♀, 2 ♂, South Dakota, Brookings Co., EcoSun Farm , 44°05'14''N, 96°47'56''W, coll. M. Perilla , reared from Spartina pectinata , sampled 23.vii.2014; 7 ♀, 9 ♂, U.S.A., South Dakota, Brookings Co., Felt Family Farm , 44°36'79''N, 96°79'70''W, reared from Spartina pectinata , emerged 02-25.viii.2014 coll. M. Perilla , ex Stenodiplosis n. sp.

Diagnosis. Distance between submedian lines 1.6 times as distance and between submedian and lateral lines; mesoscutum with 3 adnotaular setae, propodeal callus with 2 setae in one row. Antenna with F1 as long as F2, forewing 2.2 times as long as broad. Dorsellum as long as propodeum. Male antenna with scape with ventral plaque about 0.5 length of scape, situated in upper part; F1 1.05–1.1 times as long as broad, and 1.6 times as long as F2, F2 1.8 times as long as broad, F3 almost as long as F4. Forewing SMV 1.6–1.7 times as long as MV, MV 4.6– 4.8 times as long as STV.

Description. Female: Body length 1.4–1.5 mm. Forewing 1.25 mm. Body brown. Head brown; antenna brown; eye reddish. Mesosoma mostly brown, dorsellum brown. Tegula yellow. Leg with coxa dark brown, 2/3 femur foreleg and midleg brown, all 4 tarsomeres in foreleg brown, in midleg only last tarsomere brown; hindleg with femur and last tarsomere brown; gaster brown.

Head 1.1–1.2 times as broad as tall; eye height 1.4 times longer than broad and 1.9–2.0 times as long as malar space, malar sulcus straight, mouth width as long as malar sulcus. Toruli placed below the lower margin eyes. Antenna ( Figs 1–3 , 5, 6 ) with scape 3.2 times as long as broad, pedicel 2.0 times as long as broad and 2.0 times as long as scape, three anelii (1 discoid and 2 laminar); F1 1.5 times as long as broad and 1.3 times shorter than pedicel; F2 as long as F1; F2 1.7 times as long as broad; F3 1.1 times as long as broad, clava 3-segmented with F11 (terminal spine), 2.0–2.1 times as long as broad and 2.3 times as long as F3.

Thorax 1.4 times as long as broad and 1.2 times as long as gaster; mesoscutum 1.1 times as long as broad, with 3 adnotaular setae, median line distinct, metascutellum 1.25 times as long as broad, setae placed below lower half. Distance between submedian lines 1.6 times as long as distance between submedian and lateral lines. Dorsellum as long as propodeum. Propodeum 3.6–3.8 times as long as broad, smooth between median carina and postspiracular groove; spiracles placed near frontal margin of propodeum; callus with 2 setae in one row.

Forewing ( Figs 7, 8, 9 ) 2.3 times as long as broad; relative lengths of venation: MV 1.6 times as long as SMV, STV 4.2 times shorter than as MV. MV with 13 setae. Hindwing broadly rounded apically; SMV with 3 setae.

Petiole transverse, small, smooth; gaster 1.9–2.2 times as long as broad, smooth. Last tergite 1.4 times as long as broad. Cercus with 5 setae. Sheaths of ovipositor 0.75 length of gaster.

Male: Body length 0.95–1.1 mm. Forewing 0.8–0.9 mm. Antenna ( Figs 11, 12 ) with scape 2.2–2.5 times as long as wide, with ventral plaque about 0.5–0.6 length of scape, situated in upper part; pedicel 1.5–1.7 times as long as wide, with 4 anelli and 4 flagellomeres, with whorled setae; F1 1.05–1.1 times as long as broad, and 1.6 times as long as F2, F2 1.8 times as long as broad, and F3 2.1–2.3 times as long as wide, F3 almost as long as F4, F4 2.4 times as long as wide; clava 3-segmented, 5.4–5.8 times as long as broad and 2.1 times as long as F4; whorled setae of F1 reaching half of F3, whorls of F2 reaching half of F4, whorls of F3 reaching top of C1, whorls of F4 reaching middle of C2, whorls of C1 reaching half of C3 and apical sensillum.

Forewing ( Fig. 10 ) 2.1 times as long as broad; relative lengths of venation: SMV with 3 setae and 1.6–1.7 times as long as MV, MV with 13–15 setae, and 4.6–4.8 times as long as STV.

Distribution. RUSSIA, Middle Volga Region; UKRAINE, Kozarovyehi; U.S.A.: South Dakota.

Hosts. Associated with Bromis inermis in Ukraine (Kostjukov 1978), and reared from Stenodiplosis bromicola Marikovskij and Agafonova on B. inermis ( Agafonova 1962) in Russia. Collected on and reared from S. bromicola on B. inermis and S. spartinae on Spartina pectinata (Perilla López 2015, Perilla López et al. 2015a-b, and references therein).

Comments. Females of samples from Russia and the U.S.A. were compared with the type of A. bromi . They are identical in all salient characters, including the scape 3.2–3.6 times as long as broad, 1st flagellomere 1.5 times as long as wide (1.2 times in Fig. 6 ), 3rd flagellomere 1.2 times as long as broad; clava 2.0–2.2 times as long as broad, forewing 2.4 times as long as broad, SMV with 3 setae, forewing: MV with 12–13 setae and size of setae variable in different samples ( Figs 1–3 , 5–9 ). Other variations observed are in Table 1.

Based on the published evidence of host associations in Russia ( Marikovskij & Agofonova 1961, Agafonova 1962, Kosjukov 1978) and our experience in South Dakota (Perilla López 2015, Perilla López et al. 2015a-b) A. bromi is the primary parasitoid of S. bromicola and both species were introduced to North America. Aprostocetus bromi was also reared from S. geniculati Reuter on Alopecurus pratensis (Perilla López 2015, Perilla López et al. 2015b). Both the wasp and the gall midge were apparently introduced into the U.S.A. beginning in the early 1880’s through the 1910’s when a large volume of B. inermis seed was imported from the Penza region of Russia. Details of this seed shipment were given by Perilla López et al. (2015a). The plant was intended to provide a drought tolerant and cool-growing season forage for livestock, but has become a major environmental weed in most regions ( Otfinowski et al. 2007). In South Dakota A. bromi is the only known parasitoid of S. bromicola and parasitizes S. wattsi with A. nebraskensis on Andropogon gerardii and Sorghastrum nutans . It has also entered the native parasitoid guild on Stenodiplosis spartinae on Spartina pectinata ( Perilla López et al. 2015a) .

Aprostocetus bromi was also reared from gall midges on Alopecurus pratensis , another Eurasian cool-season grass, and the native warm-season grasses Andropogon gerardii , Schizachyrium scoparium , and Sorghastrum nutans . The host gall midges, S. bromicola and S. geniculati , in these introduced grasses are also Eurasian species. Aprostocetus bromi seems to be an oligophagous Eurasian introduction specialized on Stenodiplosis larvae that transferred to North American native Stenodiplosis spp., including S. spartinae (Perilla López et al. 2015a-b). The relationships of this species with other species of Aprostocetus in the same ecological guild is expected to prove interesting and may shed more light on the nature and impact of invasive species associations.

The recognition of A. bromi as an invasive parasitoid in North America exemplifies the importance of taxonomic due diligence with international specialist collaborations to resolve biodiversity questions in unstable anthropogenic communities. These discoveries also highlight the understudied guild-level ecological disruptions caused by global movements of parasitoid species that are moved between environments without regard to native species sanctity.

Figures

FIGURES 1–4. Antennae of female Aprostocetus bromi (Kostjukov) and A. nebraskensis (Girault): 1, A. bromi (Kostjukov) (Paratype, ZISP); 2, A. bromi reared from Stenodiplosis bromicola on Bromus inermis (South Dakota); 3, A. bromi reared from Stenodiplosis spartinae on Spartina pectinata (South Dakota); 4, Antenna of A. nebraskensis (Girault) (Type USNM).

FIGURES 5–6. Antennae of Aprostocetus bromi: 5, A. bromi reared from Stenodiplosis bromicola on Bromus inermis (Ulyanovsk, Russia); 6, A. bromi reared from Stenodiplosis sp. on Bromus inermis (Samara, Russia).

FIGURES 7–10. Forewings of Aprostocetus bromi: 7, female, A. bromi Kostjukov (Paratype, ZISP); 8, female, A. bromi reared from Stenodiplosis bromicola on B. inermis (South Dakota), 9, female, A. bromi reared from Stenodiplosis sp. on Andropogon gerardii (South Dakota); 10, male, A. bromi reared from S. bromicola on B. inermis (South Dakota).

FIGURES 11–12. Antennae of male Aprostocetus bromi and A. nebraskensis:. 11, A. bromi reared from S. bromicola on B. inermis (South Dakota); 12a, A. bromi reared from Stenodiplosis spartinae on Spartina pectinata (South Dakota); 12b, A. nebraskensis male (South Dakota).